<template>
  <view class="hd-subsection" :style="[subsectionStyle]">
    <view
      class="hd-item hd-clamp-1"
      :style="[itemStyle(index)]"
      @tap="click(index)"
      :class="[noBorderRight(index), 'hd-item-' + index]"
      v-for="(item, index) in listInfo"
      :key="index"
    >
      <view :style="[textStyle(index)]" class="hd-item-text hd-clamp-1">{{ item.name }}</view>
    </view>
    <view class="hd-item-bg" :style="[itemBarStyle]"></view>
  </view>
</template>

<script>
export default {
  name: 'hd-section-selector',
  props: {
    // tab的数据
    list: {
      type: Array,
      default() {
        return []
      }
    },
    // 当前活动的tab的index
    current: {
      type: [Number, String],
      default: 0
    },
    // 激活的颜色
    activeColor: {
      type: String,
      default: '#303133'
    },
    // 模式选择，mode=button为按钮形式，mode=subsection时为分段模式
    mode: {
      type: String,
      default: 'button'
    },
    // 字体大小，单位rpx
    fontSize: {
      type: [Number, String],
      default: 28
    },
    // 是否开启动画效果
    animation: {
      type: Boolean,
      default: true
    },
    // 组件的高度，单位rpx
    height: {
      type: [Number, String],
      default: 70
    },
    // 激活tab的字体是否加粗
    bold: {
      type: Boolean,
      default: true
    },
    // mode=button时，组件背景颜色
    bgColor: {
      type: String,
      default: '#eeeeef'
    },
    // mode = button时，滑块背景颜色
    buttonColor: {
      type: String,
      default: '#ffffff'
    },
    // 在切换分段器的时候，是否让设备震一下
    vibrateShort: {
      type: Boolean,
      default: false
    }
  },
  data() {
    return {
      listInfo: [],
      itemBgStyle: {
        width: 0,
        left: 0,
        backgroundColor: '#ffffff',
        height: '100%',
        transition: ''
      },
      currentIndex: this.current,
      buttonPadding: 3, // mode = button 时，组件的内边距
      borderRadius: 5, // 圆角值
      firstTimeVibrateShort: true // 组件初始化时，会触发current变化，此时不应震动
    }
  },
  watch: {
    current: {
      immediate: true,
      handler(nVal) {
        this.currentIndex = nVal
        this.changeSectionStatus(nVal)
      }
    }
  },
  created() {
    // 将list的数据，传入listInfo数组，因为不能修改props传递的list值
    // 可以接受直接数组形式，或者数组元素为对象的形式，如：['简介', '评论'],或者[{name: '简介'}, {name: '评论'}]
    this.listInfo = this.list.map((val, index) => {
      if (typeof val !== 'object') {
        let obj = {
          width: 0,
          name: val
        }
        return obj
      } else {
        val.width = 0
        return val
      }
    })
  },
  computed: {
    // 设置mode=subsection时，滑块特有的样式
    noBorderRight() {
      return index => {
        if (this.mode !== 'subsection') return
        let classs = ''
        // 不显示右边的边框
        if (index < this.list.length - 1) classs += ' hd-none-border-right'
        // 显示整个组件的左右边圆角
        if (index === 0) classs += ' hd-item-first'
        if (index === this.list.length - 1) classs += ' hd-item-last'
        return classs
      }
    },
    // 文字的样式
    textStyle() {
      return index => {
        let style = {}
        // 设置字体颜色
        if (this.mode === 'subsection') {
          if (index === this.currentIndex) {
            style.color = '#ffffff'
          } else {
            style.color = this.activeColor
          }
        } else {
          if (index === this.currentIndex) {
            style.color = this.activeColor
          } else {
            style.color = this.inactiveColor
          }
        }
        // 字体加粗
        if (index === this.currentIndex && this.bold) style.fontWeight = 'bold'
        // 文字大小
        style.fontSize = this.fontSize + 'rpx'
        return style
      }
    },
    // 每个分段器item的样式
    itemStyle() {
      return index => {
        let style = {}
        if (this.mode === 'subsection') {
          // 设置border的样式
          style.borderColor = this.activeColor
          style.borderWidth = '1px'
          style.borderStyle = 'solid'
        }
        return style
      }
    },
    // mode=button时，外层view的样式
    subsectionStyle() {
      let style = {}
      style.height = uni.upx2px(this.height) + 'px'
      if (this.mode === 'button') {
        style.backgroundColor = this.bgColor
        style.padding = `${this.buttonPadding}px`
        style.borderRadius = `${this.borderRadius}px`
      }
      return style
    },
    // 滑块的样式
    itemBarStyle() {
      let style = {}
      style.backgroundColor = this.activeColor
      style.zIndex = 1
      if (this.mode === 'button') {
        style.backgroundColor = this.buttonColor
        style.borderRadius = `${this.borderRadius}px`
        // style.bottom = `${this.buttonPadding}px`;
        style.height = uni.upx2px(this.height) - this.buttonPadding * 2 + 'px'
        style.zIndex = 0
      }
      return Object.assign(this.itemBgStyle, style)
    }
  },
  mounted() {
    setTimeout(() => {
      this.getTabsInfo()
    }, 10)
  },
  methods: {
    // 改变滑块的样式
    changeSectionStatus(nVal) {
      if (this.mode === 'subsection') {
        // 根据滑块在最左边和最右边时，显示左边和右边的圆角
        if (nVal === this.list.length - 1) {
          this.itemBgStyle.borderRadius = `0 ${this.buttonPadding}px ${this.buttonPadding}px 0`
        }
        if (nVal === 0) {
          this.itemBgStyle.borderRadius = `${this.buttonPadding}px 0 0 ${this.buttonPadding}px`
        }
        if (nVal > 0 && nVal < this.list.length - 1) {
          this.itemBgStyle.borderRadius = '0'
        }
      }
      // 更新滑块的位置
      setTimeout(() => {
        this.itemBgLeft()
      }, 10)
      if (this.vibrateShort && !this.firstTimeVibrateShort) {
        // 使手机产生短促震动，微信小程序有效，APP(HX 2.6.8)和H5无效
        // #ifndef H5
        uni.vibrateShort()
        // #endif
      }
      // 第一次过后，设置firstTimeVibrateShort为false，让其下一次可以震动(如果允许震动的话)
      this.firstTimeVibrateShort = false
    },
    click(index) {
      // 不允许点击当前激活选项
      if (index === this.currentIndex) return
      this.currentIndex = index
      this.changeSectionStatus(index)
      this.$emit('change', Number(index))
    },
    // 获取各个tab的节点信息
    getTabsInfo() {
      let view = uni.createSelectorQuery().in(this)
      for (let i = 0; i < this.list.length; i++) {
        view.select('.hd-item-' + i).boundingClientRect()
      }
      view.exec(res => {
        if (!res.length) {
          setTimeout(() => {
            this.getTabsInfo()
          }, 10)
        }
        // 将分段器每个item的宽度，放入listInfo数组
        res.map((val, index) => {
          this.listInfo[index].width = val.width
        })
        // 初始化滑块的宽度
        if (this.mode === 'subsection') {
          this.itemBgStyle.width = this.listInfo[0].width + 'px'
        } else if (this.mode === 'button') {
          this.itemBgStyle.width = this.listInfo[0].width + 'px'
        }
        // 初始化滑块的位置
        this.itemBgLeft()
      })
    },
    itemBgLeft() {
      // 根据是否开启动画效果，
      if (this.animation) {
        this.itemBgStyle.transition = 'all 0.35s'
      } else {
        this.itemBgStyle.transition = 'all 0s'
      }
      let left = 0
      // 计算当前活跃item到组件左边的距离
      this.listInfo.map((val, index) => {
        if (index < this.currentIndex) left += val.width
      })
      // 根据mode不同模式，计算滑块需要移动的距离
      if (this.mode === 'subsection') {
        this.itemBgStyle.left = left + 'px'
      } else if (this.mode === 'button') {
        this.itemBgStyle.left = left + this.buttonPadding + 'px'
      }
    }
  }
}
</script>

<style lang="scss" scoped>
.hd-subsection {
  display: flex;
  align-items: center;
  overflow: hidden;
  position: relative;
}

.hd-item {
  flex: 1;
  text-align: center;
  font-size: 26rpx;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #000000;
  display: inline-flex;
  padding: 0 6rpx;
}

.hd-item-bg {
  background-color: #fff;
  position: absolute;
  z-index: -1;
}

.hd-none-border-right {
  border-right: none !important;
}

.hd-item-first {
  border-top-left-radius: 8rpx;
  border-bottom-left-radius: 8rpx;
}

.hd-item-last {
  border-top-right-radius: 8rpx;
  border-bottom-right-radius: 8rpx;
}

.hd-item-text {
  transition: all 0.35s;
  color: #333;
  display: flex;
  align-items: center;
  position: relative;
  z-index: 99;
}
</style>
